Hydraulic brake control assembly responsive to vehicular deceleration

Abstract

An improved hydraulic brake control assembly for automotive vehicles having a proportioning valve for regulating the hydraulic pressure applied to the rear wheel brakes from a master brake cylinder in accordance with vehicular load. A control device responsive to vehicular deceleration and hydraulic pressure from the master brake cylinder controls the proportioning valve by a slidable piston of the control device applying an urging force on the proportioning valve varied in response to the hydraulic pressure applied to the slidable piston. The hydraulic pressure from the master brake cylinder applied to the slidable piston is modified by first valve, a second pressure-sensitive valve and an orifice. The first valve controls admission of the hydraulic pressure to the slidable piston in response to predetermined vehicular deceleration, the orifice and the second valve being in parallel, the hydraulic pressure normally being supplied to the slidable piston through the orifice. The normally-closed second valve is opened when a predetermined hydraulic pressure difference is reached on opposing sides of the orifice for supplying the hydraulic pressure to the slidable piston without pressure throttling by the orifice. The proportioning valve therefore operates to provide a proper hydraulic pressure to the rear wheel brakes in accordance with different vehicular loads and braking applications.

What is claimed is: 
     
       1. An improved hydraulic brake control assembly for automotive vehicles having front and rear wheel brake means and a hydraulic braking master cylinder fluidically connected to each of said brake means comprising: a. valve proportioning means interposed between said master cylinder and at least one of said wheel brake means for regulating the hydraulic pressure applied to said at least one of said wheel brake means from said master cylinder in accordance with vehicular load, wherein said valve proportioning means includes a reciprocable proportioning piston subjected at a first section formed in said valve proportioning means to the hydraulic pressure in said at least one of said wheel brake means and at a second section formed in said valve proportioning means to the hydraulic pressure from said master cylinder, said proportioning piston being normally urged to a position allowing hydraulic pressure communication between said first and second sections;   b. control means responsive to vehicular deceleration and hydraulic pressure from said master cylinder for controlling said valve proportioning means in accordance with vehicular load wherein said control means includes (i) slidable piston means engaged with said reciprocable proportioning piston for applying an urging force on said proportioning piston varied in response to hydraulic pressure applied to said piston means, said piston means normally urging said proportioning piston to an open hydraulic pressure communication position;   (ii) first passage means for supplying hydraulic pressure from said master cylinder to said piston means;   (iii) first valve means interposed in said first passage means for controlling admission of the hydraulic pressure supplied to said piston means in response to vehicular deceleration;   (iv) orifice means interposed in said first passage means for throttling the hydraulic pressure supplied to said piston means; and   (v) second valve means positioned parallel to said orifice means in said first passage means and normally closed, said second valve means having a valve portion being opened when a predetermined difference in hydraulic pressure is reached on opposite sides of said orifice means for supplying the hydraulic pressure to said piston means without pressure throttling by said orifice means.     
     
     
       2. An improved hydraulic brake control assembly as set forth in claim 1 wherein said second valve means is a relief valve, and wherein said orifice means and relief valve are positioned in said first passage means between said first valve means and said slidable piston means. 
     
     
       3. An improved hydraulic brake control assembly as set forth in claim 2 wherein said control means further comprises third valve means positioned in said first passage means between said first valve means and said orifice means and said relief valve, said third valve means normally urged closed for preventing supply of hydraulic pressure to said orifice and relief valve and opened in response to a predetermined hydraulic pressure for admitting the hydraulic pressure to said orifice and relief valve. 
     
     
       4. An improved hydraulic brake control assembly as set forth in claim 1 wherein said second valve means is a metering valve, and wherein said first valve means is positioned in said first passage means between said parallel orifice means and metering valve and said slidable piston means. 
     
     
       5. An improved hydraulic brake control assembly as set forth in claim 4 wherein said control means further comprises third valve means positioned in said first passage means between said orifice means and metering valve and said first valve means, said third valve means normally urged closed for preventing supply of hydraulic pressure to said first valve means and opened in response to a predetermined hydraulic pressure for admitting the hydraulic pressure to said first valve means. 
     
     
       6. An improved hydraulic brake control assembly as set forth in claim 1 wherein said at least one wheel brake means is said rear brake means and wherein said front wheel brake means is directly connected to said master cylinder. 
     
     
       7. An improved hydraulic brake control assembly as set forth in claim 6 further comprising conduits for connecting said master cylinder to each of said front and rear wheel brake means, said conduit to said rear wheel brake means providing greater hydraulic retardation than said conduit to said front wheel brake means. 
     
     
       8. An improved hydraulic brake control assembly as set forth in claim 1 further comprising a housing for said valve proportioning means and control means having an inlet connected to said master cylinder, an outlet connected to said at least one wheel brake means, and a second passage means formed between said inlet and outlet in which is positioned said reciprocable proportioning piston, and wherein said first passage means is formed in said housing connected at one end to said second passage means at said second section and at the other end to said slidable piston means. 
     
     
       9. An improved hydraulic brake control assembly as set forth in claim 8 wherein said slidable piston means comprises a slidable piston mounted in said housing coaxially with said reciprocable proportioning piston and a spring positioned between one end of said slidable piston and opposing end of said reciprocable proportioning piston for normally urging said proportioning piston to an open position and wherein a first pressure control chamber is formed in said first passage means at the other end of said slidable piston for moving said slidable piston to vary the urging force of said spring exerted on said reciprocable proportioning piston in response to hydraulic pressure supplied to said first pressure control chamber. 
     
     
       10. An improved hydraulic brake control assembly as set forth in claim 9 wherein said first valve means is an inertia-responsive valve cooperative with said first passage means and being normally open, said inertia-responsive valve closing said first passage means to hydraulic pressure upon application of a predetermined vehicular deceleration in accordance with vehicular load, and wherein said orifice means and second valve means are incorporated in a relief valve assembly positioned between said inertia-responsive valve and said first pressure control chamber with a body portion in sealing engagement with said first passage means, an orifice formed in said body portion for throttling hydraulic pressure supplied therethrough to said first pressure control chamber, and a normally closed relief valve portion arranged in parallel to said orifice, said relief valve portion being opened when a predetermined difference in hydraulic pressure is reached on opposite sides of said orifice in said first passage means for supplying hydraulic pressure therethrough to said first pressure control chamber without the throttling effect of said orifice. 
     
     
       11. An improved hydraulic brake control assembly as set forth in claim 10 wherein said first passage means includes a second pressure control chamber formed therein between said inertia-responsive valve and first pressure control chamber, and wherein a third valve means is positioned at one end of said second pressure control chamber for controlling admission of hydraulic pressure to said second pressure control chamber from said inertia-responsive valve, said third valve means being normally urged closed to prevent supply of hydraulic pressure to said second pressure control chamber and opened in response to a predetermined hydraulic pressure for admitting hydraulic pressure to said second pressure control chamber, and wherein said relief valve assembly is positioned at the other end of said second pressure control chamber with one side of said orifice being subjected to hydraulic pressure in said second pressure control chamber and the other side of said orifice being subjected to hydraulic pressure in said first pressure control chamber. 
     
     
       12. An improved hydraulic brake control assembly as set forth in claim 11 wherein said inertia-responsive valve comprises a seat positioned in said first passage means with a through-hole formed therein for admitting hydraulic pressure to said third valve means and a ball cooperative with said seat for closing said through-hole to prevent hydraulic pressure to said third valve means upon application of the predetermined vehicular deceleration. 
     
     
       13. An improved hydraulic brake control assembly as set forth in claim 11 wherein shoulders are formed at the ends of said second pressure control chamber and wherein a spring is interposed between said third valve means and said relief valve assembly for urging said third valve means to a normally closed position against one shoulder, and said relief valve assembly to a sealing position against the other shoulder, and wherein said third valve means is opened in response to the application of a hydraulic pressure which overcomes the urging force of said spring. 
     
     
       14. An improved hydraulic brake control assembly as set forth in claim 13 wherein said third valve means includes a valve portion for allowing return of hydraulic pressure from said first pressure control chamber to said master cylinder through said first passage means when braking application on said master cylinder is released. 
     
     
       15. An improved hydraulic brake control assembly as set forth in claim 9 wherein said first valve means is an inertia-responsive valve cooperative with said first passage means and being normally open, said inertia-responsive valve closing said first passage means to hydraulic pressure upon application of a predetermined vehicular deceleration in accordance with vehicular load, and wherein said orifice means and second valve means are incorporated in a metering valve assembly positioned in said first passage means before said inertia-responsive valve with a fixed assembly body, a metering piston slidably positioned in said body and normally urged in sealing engagement with said first passage means, and an orifice formed in said slidable metering piston for throttling hydraulic pressure supplied therethrough to said inertia-responsive valve, and wherein said metering piston is moved to an open position when a predetermined difference in hydraulic pressure is reached on opposite sides of said orifice in said first passage means for supplying hydraulic pressure therethrough to said inertia-responsive valve without the throttling effect of said orifice. 
     
     
       16. An improved hydraulic brake control assembly as set forth in claim 15 wherein said first passage means includes a second pressure control chamber formed therein between said metering valve assembly and first pressure control chamber, and wherein a third valve means is positioned at one end of said second pressure control chamber for controlling admission of hydraulic pressure to said second pressure control chamber from said metering valve assembly, said third valve means being normally urged closed to prevent supply of hydraulic pressure to said second pressure control chamber and opened in response to a predetermined hydraulic pressure for admitting hydraulic pressure to said second control chamber, and wherein said inertia-responsive valve is positioned at the other end of said control chamber with one side being subjected to hydraulic pressure in said second pressure control chamber and the other side being subjected to hydraulic pressure in said first pressure control chamber. 
     
     
       17. An improved hydraulic brake control assembly as set forth in claim 15 wherein shoulders are formed at the ends of said second pressure control chamber and wherein said inertia-responsive valve comprises a seat positioned against one shoulder of said second pressure control chamber with a through-hole formed therein for admitting hydraulic pressure to said first pressure control chamber and a ball cooperative with said seat for closing said through-hole to prevent hydraulic pressure to said first pressure control chamber upon application of the predetermined vehicular decleration. 
     
     
       18. An improved hydraulic brake control assembly as set forth in claim 17 wherein a spring is positioned for urging said third valve means to a normally closed position against the shoulder formed at the other end of said second pressure control chamber and wherein said third valve means is opened in response to the application of a hydraulic pressure which overcomes the urging force of said spring. 
     
     
       19. An improved hydraulic brake control assembly as set forth in claim 18 wherein said third valve means includes a valve portion for allowing return of hydraulic pressure from said first pressure control chamber to said master cylinder through said first passage means when braking application on said master cylinder is released.